Quantitative Estimates of Temperature Changes Over the Last 2700 Years in Michigan Based on Pollen Data
Quantitative Estimates of Temperature Changes Over the Last 2700 Years in Michigan Based on Pollen Data
复制标题
基于花粉数据对密歇根州过去 2700 年温度变化的定量估计
DOI：
10.1016/0033-5894(81)90101-0
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发表时间：
1981
影响因子：
2.3
通讯作者：
J. C. Bernabo
中科院分区：
文献类型：
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作者：
J. C. Bernabo
过去 2700 年的气温是利用来自密歇根州西北部的过时花粉数据估算的。花粉数据是从沿 75 公里样带的四个湖泊的沉积岩芯中采样的，其中两个西部湖泊周围是细粒冰碛土，东部湖泊周围是沙质冲刷土壤。基于沙地花粉数据的气候重建显示，温度变化比其他地点的重建要小，因为沙地植被组成的变化受到土壤的限制。研究的其中一个岩心是通过计算可见的年度叠片（varve）来确定年代的。其他湖泊的岩心是根据每个岩心的三个放射性碳年代测定以及历史上确定的定居点地平线的年龄来测年的。使用四个地点之间的花粉地层相关性对所有时间尺度进行交叉检查。使用覆盖整个下密歇根州的现代花粉和气候数据网络开发了校准函数。根据该校准函数，马里恩湖 2700 年的重建表明，30 年极端平均值之间的估计生长季节温度范围为 1.3°C。大约在大约之前，温和的条件持续存在。公元 400 年，但大约在公元 400 年之间发生了一段寒冷的时期。公元 500 年和 800 年。公元 1000 年至 1200 年是最后一次气温大约等于 1931 年至 1960 年平均气温的时期。公元 1200 年之后出现了长时间的降温，到 1700 年代气温比 1931-1960 年的平均温度低 1°C。大约 0.5°C 的升温表明。公元 1750 年至 1850 年。1830 年代马里恩湖的估计温度与该时期的仪器数据一致，这为校准函数结果提供了一些验证。
Temperatures for the past 2700 yr are estimated using well-dated pollen data from northwestern lower Michigan. The pollen data were sampled from sediment cores of four lakes along a 75-km transect, with fine-grained morainic soils around the two western lakes and sandy outwash soils around the lakes to the east. Climatic reconstructions based on the pollen data from the sandy sites show less temperature change than the reconstructions from the other sites, because variations in the composition of the vegetation at the sandy sites are edaphically restricted. One of the cores studied was dated by counting visible annual laminations (varves). The cores from the other lakes were dated based on three radiocarbon dates per core as well as the historically determined age of the settlement horizons. All the time scales were cross-checked using pollen-stratigraphic correlation between the four sites. A calibration function was developed using a network of modern pollen and climate data covering all of lower Michigan. Based on this calibration function, the 2700-yr reconstruction for Marion Lake indicates an estimated growing-season temperature range of 1.3°C between extreme 30-yr means. Mild conditions persisted prior to ca. A.D. 400, but a cold interval occurred between ca. A.D. 500 and 800. The well-marked warm period evident from ca. A.D. 1000 to 1200 was the last time when temperatures were about equal to the 1931–1960 mean. A prolonged longed cooling occurred after A.D. 1200 and reached 1°C below the 1931–1960 mean by the 1700s. A warming of 0.5°C is indicated from ca. A.D. 1750 to 1850. The estimated temperatures for the 1830s at Marion Lake agree with the instrumental data for that period and this provides some validation of the calibration-function results.